Embodiments of the invention relate generally to electrical conversion system, and more particularly, to a DC/DC conversion system with magnetically coupled inductors and a multiphase buck component.
Automotive power electronics have been rapidly growing in recent years to meet environmental regulations and address an expanding electric and hybrid electric vehicle (EV/HEV) market. It is widely recognized that HEVs, such as mild hybrid electric vehicles (mHEV), are suitable for addressing fuel saving needs and CO2 emission reductions. An increasing number of vehicles include a start-stop system which shuts down the engine while the car is stationary to save fuel. However, the actual use of the start-stop system is often limited by the need to maintain power levels for many of the features and auxiliary systems in vehicles such as navigation, heating, air-conditioning, radio, and other electronic equipment.
The power demands of these features have resulted in calls for a 48V electrical system, which provides more electrical capacity but avoids costly high-voltage batteries and power electronics used in traditional HEVs. The 48V electrical system contains a small electric generator that can assist the engine with up to tens of kilowatts of power and a small lithium-ion battery pack. A new lithium-ion 12-V battery is also included to assist start-stop setup by storing regenerative breaking energy for restarting. A conventional 48V mHEV system contains two batteries, 48V and 12V, with a DC/DC converter coupled between for energy exchange. Since the output power in this system typically varies from 3.5 kW to 5 kW, it is very crucial to maintain high average efficiencies over different output powers. While the 48V electrical system is typically designed for mHEVs, the system may also be used in data centers, communication centers, point of load systems, and medical applications as nonlimiting examples.
Conventional buck or buck/boost topologies are commonly used for the 48V system. However, this topology includes a limited range of inductor ripple cancellation over different duty ratios and a limited maximum ripple reduction rate. As such, there is a need for a DC/DC conversion system which addresses these issues while improving efficiency.